#include <iostream>

using namespace std;

int ans = 0;
int f(int x, int y) {
	if(3 == x || 4 == y) {
		return 1;
	}
	
	return f(x+1, y) + f(x, y+1);
}

int main() {
	
	cout << f(0, 0) << endl;
	
	return 0;
}
